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The butterfly plastic zone theory based on Mohr Coulomb criterion has been widely used in coal mine production. In order to verify the universality of the theory, it is necessary to compare the distribution of plastic zone under different strength criteria. Based on the elastic-plastic mechanics, the principal stress distribution function around the circular tunnel is deduced in the paper, and the boundary and radius of the plastic zone under different strength criteria are calculated. The results show that the change laws of the plastic zone around the circular tunnel under different strength criteria has the following commonness: firstly, with the increase of the lateral pressure coefficient, the shape of the plastic zone presents the change laws of “circle ellipse butterfly”; Secondly, with the increase of the lateral pressure coefficient, the radius of the plastic zone is exponential distribution, while the characteristic value is different when the radius of the plastic zone is infinite. At same time, it shows that the butterfly plastic zone has a low sensitivity dependence on the strength criterion, no matter which strength criterion is adopted, and the butterfly plastic zone will inevitably appear in the surrounding rock mass of circular tunnel in the high deviator stress environment; The plastic zone with butterfly shape is highly sensitive to the stress change, and the small stress change may promote the expansion of the plastic zone. This result is significant for us to understand and prevent rock engineering disasters and accidents.
Different relational dynamics make relationships evolve within entourages. They are here mainly explored from the Caen panel, whose longitudinal dimension allows it to capture detailed movements over time. The diagram of relational dynamics identified in Chapter 3 is taken up again by detailing the main movements articulating relations, contexts and networks: polyvalence/specialization, singularization/embedding, and connection/dissociation. The ways in which these dynamics appear, their frequency, and their evolution over the time of the relationship, and over biographical time, are highlighted here.
Social relations are defined by considering the different dimensions involved: interaction, knowledge, emotional involvement, and, more generally, the "driving force" of the tie, which are its essential elements. This characterization of relationships is continued by mentioning qualities that are very important for their becoming: the multiplexity and "strength" of the ties. To explain the link between relationships, networks, and social circles, the different scales at which the entourage can be considered are then evoked. The questions of the homogeneity of relationships, the resources they may constitute, as well as the different ways in which they can be inscribed in social circles are also addressed. Finally, the various types of regulation involved in the positioning of relationships are presented.
At the beginning of the 1990s, the Internet was starting to become fairly widely used in academic circles. This development raised questions within the community of social science researchers who were studying social networks. Among them was of course that of the changes in relational flows and structures (connectivity, size, density, and composition of personal networks, etc.) that might occur as a result of the increasing diversification and sophistication of communication technologies. For this chapter, we draw on two recent original surveys in addition to the two on which our analyses have so far been based. The first is a questionnaire-based survey conducted in January and February 2014 among 2,700 young people aged between 15 and 25 living in the Toulouse area. The second survey is a detailed questionnaire filled in during face-to-face interviews by some 470 individuals aged 60 and over (the oldest was 100 at the time of the survey) in the Toulouse area. The changes seem to be tending in the direction of a slight reduction in strong ties, an increase in weak or even very weak ties and a strengthening of relational inequalities and homophily.
To enhance math achievement, numerous instructional strategies have been and will continue to be developed. Neither typical instructional procedures nor new methods for teaching math will be successful unless students choose to engage in assigned math activities. Two factors that can influence choice are response effort and reinforcement strength. Enhancing students’ basic math fact fluency can reduce the effort required to complete simple and more complex math tasks, making it more likely that students will choose to engage in math activities. Four evidence-based procedures designed to enhance basic math fact fluency are described (i.e., Cover, Copy, and Compare; Taped Problems; Explicit Timing; and Detect, Practice, and Repair). Also, procedures designed to enhance reinforcement for choosing to engage in math tasks are reviewed. These procedures include the Additive Interspersal Procedure, altering longer assignments into multiple briefer assignments, and applying interdependent group-oriented bonus rewards.
In the present paper, the authors investigated the microstructures and mechanical properties of dual-phase Co–Ti–V-based superalloys with different additions of Ru. The results showed that with the increase of Ru contents, the size of γ′ precipitates of the alloy gradually raised, the volume fraction of γ′ phase slightly, and the lattice misfit between γ/γ′ phases increased. Ru was enriched in the γ′ phase, and the elemental partition coefficients (KX = Cγ′/Cγ) of Ti and V increased with the increment of Ru. The Ru contents have no remarkable influence on the solvus temperatures of γ′ in the Co–Ti–V alloys. The yield strength at 1000 °C of the Co–10Ti–11V–0.5Ru alloy was the highest, while the yield strength of the 1Ru alloy was the smallest. Transmission electron microscopy and scanning electron microscopy observations showed that the γ′ shape in the compressed specimen containing 0.5Ru remain integrated, while the γ′ in other alloys were cut into several parts.
The subject here is the absorption coefficient, expressing the net power loss from the field over a unit path. At its heart is the line shape, which may be identified with the power spectral density function for fluctuations of the active dipole in the presence of an equilibrium bath of perturbers, and, as such, should satisfy the fluctuation–dissipation theorem. The more general properties of the absorption coefficient, which must reflect this balance, are first examined in some detail, particularly for the Van Vleck–Huber form. It is then shown that this, when expanded as a sum over individual lines, may be folded into more compact expressions. Outside the line core, these expressions must incorporate the fluctuation–dissipation theorem, and special attention is given to distinguish this case and that of the core itself, where it is of no consequence. Even the very general Fano theory does not, as it stands, satisfy the theorem, and can be used for the far-wing line shape only if these expressions are modified. Finally, some account is given of how they may be used with a molecular line database, and how a calculation of radiative transfer might proceed in the simplest of cases.
We evaluated the effects of fermentation time and acid casein content on the microbial rennet obtained by solid-state fermentation using wheat bran as the carbon source. The experiments used two fermentation times (72 and 96 h), while acid casein content was 1.5, 2.0, 2.5, and 3.0 g. Rennet strength from eight enzymatic extracts was measured using pasteurized whole milk. Rennet strength of samples from 72 h of fermentation showed an increase when acid casein content increased. The rennet strength increased at 96 h of fermentation with increasing amount of casein (up to 2.5 g), and then decreased with the largest addition (3.0 g) of casein. Coagulation time for the sample with highest rennet strength was 420 s.
Self-control problems are ubiquitous and a frequent target of behavior change interventions. From a theoretical perspective, self-control is not a unitary phenomenon but rather encompasses a vast and complex set of interacting aspects or key components. As the science of self-control keeps growing, the integration of these key components becomes increasingly important. To this end, an integrative self-control theory (integrative self-control theory) is proposed – a mid-level theory that connects seven psychological components or “hubs” of self-control: (1) desire; (2) self-control goal; (3) self-control conflict; (4) self-control motivation; (5) self-control capacity; (6) self-control effort; and (7) constraints. This chapter addresses the issue of behavior change from the perspective of this integrative theory of self-control. A brief introduction to the theory is followed by demonstrations on how it can be used to identify and classify various behavior change techniques in the self-control domain. Moreover, differences and similarities of integrative self-control theory next to more general frameworks such as the commitment-opportunity-motivation behavior model (Michie, Atkins, & West, 2014) are outlined, avenues for future research highlighted, and general recommendations for behavior change from the perspective integrative self-control theory provided.
The final chapter grapples with a critical question for the entire book: Has greater access to other people through media (connectivity) contributed to people’s sense of connection or furthered a sense of isolation? The current nearly constant state of connectivity is contrasted with the importance of connection through social interaction with close others. This chapter reviews evidence of declining rates of social interaction among Americans. Bringing back theories and perspectives introduced throughout this book, this chapter examines why connectivity does not necessarily make us feel more connected. Finally, the chapter offers suggestions for gaining the most from the promise of connectivity by establishing mediated social interaction routines.
Nonclassical theories of truth that take truth to be transparent have some obvious advantages over any classical theory of truth (which must take it as nontransparent on pain of inconsistency). But several authors have recently argued that there’s also a big disadvantage of nonclassical theories as compared to their “external” classical counterparts: proof-theoretic strength. While conceding the relevance of this, the paper argues that there is a natural way to beef up extant internal theories so as to remove their proof-theoretic disadvantage. It is suggested that the resulting internal theories are preferable to their external counterparts.
Impaired isometric muscle strength was previously reported in adults with Fontan circulation. However, it is unclear if this impairment is present in children and adolescents with Fontan circulation. We investigated isometric muscle strength of the lower limb in patients (6–18 years) with Fontan circulation in comparison with healthy controls.
In this cross-sectional study, 43 patients (6–18 years) with Fontan circulation and 43 age- and sex-matched controls were included. Isometric knee extension and plantar flexion muscle strength were assessed using dynamometry (Newton, N). Lean mass of the legs was assessed with dual-energy X-ray absorptiometry. Analyses were performed on group level (n = 43), and for subgroups that included children aged 6–12 years (n = 18) and adolescents aged 13–18 years (n = 25).
On group level, the patients with Fontan circulation had impaired isometric knee extension strength in comparison with the controls (p = 0.03). In subgroup analyses, impaired isometric knee extension strength was present in the adolescents (p = 0.009) but not in the children groups. For plantar flexion, there was no difference between patients and controls. There was no difference in lean mass between patients and controls (9.6 ± 4.3 kg vs. 10.8 ± 5.6 kg, p = 0.31). However, the lean mass was highly correlated to isometric knee extension strength (patients r = 0.89, controls r = 0.96, p < 0.001) and isometric plantar flexion strength (patients r = 0.7, controls r = 0.81, p < 0.001).
The finding of impaired isometric knee extension muscle strength in adolescents (13–18 years) with Fontan circulation and no corresponding impairment in the children group (6–12 years) could imply that isometric muscle strength gets more impaired with age.
The longitudinal relationship between muscle strength, dietary intake and physical activity among adolescents is not well understood. We investigated the trend and longitudinal effects of dietary intakes and physical activity scores on muscle strength in adolescents. This prospective cohort study consisted of 436 adolescents (134 males; 302 females) aged 13 years at baseline (2012) who were followed up at the ages of 15 (2014) and 17 (2016) years, respectively. We measured muscle strength using a calibrated hand dynamometer, estimated dietary intake with a 7-d dietary history and physical activity scores with a validated physical activity questionnaire for older children. A generalised estimating equation was used to examine the effect of dietary intakes and physical activity on muscle strength changes. The analysis was performed separately by sex. The muscle strength for males and females had increased within the 5-year period. The dietary intakes (energy and macronutrients) also increased initially but plateaued after the age of 15 years for both sexes. Females recorded a significant declining trend in physical activity scores compared with males as they grew older. A significant positive longitudinal relationship was found between protein (β = 0·035; P = 0·016), carbohydrate intake (β = 0·002; P = 0·013) and muscle strength among males. However, no longitudinal relationship was found between dietary intake, physical activity and muscle strength among females. Higher protein and carbohydrate intake among males was associated with higher muscle strength but was not observed in females. Nutrition and physical activity focusing on strength building are required in early adolescence and need to be tailored to males and females accordingly.
In the present study, the effect of Al addition on microstructure evolution, mechanical properties, and wear performances of a newly developed Ni–Si-containing complex brass was studied. The results showed that with increasing Al content from 0 to 3 wt%, the corresponding strengthening phase evolves from δ-Ni2Si to [Ni(Al)]2Si phases. Simultaneously, it is of great interest that the increasing Al addition also brings about a remarkable change in morphology of the secondary strengthening phase from dendrite and thin rod to regular block. Additionally, the hardness, yield strength and tensile strength of complex brass effectively increase with increasing Al content, and the fracture mechanism transforms from cleavage failure and microvoids accumulation fracture to cleavage failure. It was also found that the brass with adding 3 wt% Al exhibits the solidification microstructure with the uniform distribution of the block-shaped strengthening phase and has the best wear resistance. This present study provides a potential strategy for further improving the comprehensive performance of existing complex brass.
Distinguished by a marked combination of high strength and high fracture toughness, 18Ni-300 maraging steel (MS) is widely used for intricate tool and die applications. MS is also amenable to the powder bed fusion additive manufacturing process, providing unique opportunities to make small features and incorporate cooling channels in molds. In this study, tensile test samples were fabricated using selective laser melting to investigate the effects of built height and orientations on the evolution of the microstructure and the mechanical properties of the samples. The microstructure of the as-fabricated samples consists of the primary α-martensite phase and fine cellular microstructure (~0.66–0.83 μm) with the retained austenite γ-phase aggregated at the boundaries of the cells, resulting in an enhanced mechanical performance compared with traditional counterparts under the same condition (without post-heat treatments). Random grain orientations with weak textures are revealed in all samples. The XY-built samples display better tensile performance when compared to the Z-built samples due to the fine grain sizes and the retained γ phase. The bottom of the Z-built sample exhibits a higher hardness than other parts of the sample, which could be attributed to its finer cellular structure.
Background and Objective. A growing body of literature indicates a significant contribution and role of positive and negative emotions (specifically expressivity) in post-traumatic stress disorder's (PTSD) symptomatology. The current study examined the facet-level relationships between emotional expressivity and PTSD. Specifically, we investigated which emotional expressivity dimension (impulse strength, negative emotional expressivity, and positive emotional expressivity) most strongly related to DSM-5 PTSD symptom clusters severity (intrusions, avoidance, negative alterations in cognition and mood, and alterations in arousal and reactivity). Methods. The sample of 123 trauma-exposed participants seeking mental health treatment completed the PTSD Checklist for DSM-5 (PCL-5) and the Berkeley Expressivity Questionnaire (BEQ). Results. Results of multivariate multiple regression analysis indicated that only intensity of emotion and difficulty in controlling such emotions (i.e., impulse strength) was strongly related to all four PTSD symptom clusters. The valence of emotional expressivity (positive or negative) was not related to any of the PTSD symptom clusters. Conclusions. Study findings highlight the role of emotional expressivity, specifically impulse strength, in PTSD's symptomatology and may inform guidelines for emotion-focused clinical work for trauma-exposed individuals with PTSD symptoms.
Using an anti-icing coating to prevent ice accretion on the drill surface is a feasible solution to address the drilling difficulties in warm ice. In this study, four types of commercially available hydrophobic coating materials were tested to evaluate their water repellency and anti-icing properties, namely, a mixture of silica and fluorocarbon resin with polytrifluoroethylene, modified Teflon, silica-based emulsion and an acrylic-based copolymer. Their water contact angles are ~107°, 101°, 114° and 95°, respectively. All these hydrophobic coatings can significantly reduce the strength of the ice adhesion within a temperature range of −10 to −30°C on a planar or curved surface. The coating of an acrylic-based copolymer, in particular, can reduce the average tensile strength and the shear strength of the ice adhesion by 87.08 and 97.11% on planar surfaces at −30°C, and by 98.06 and 96.15% on a curved surface, respectively. The main challenge in the practical application of these coatings is their durability. An acrylic-based copolymer coating will lose its water repellency performance after 140 cycles of abrasion. The shear strength of ice adhered on curved surfaces coated with this material will approach that achieved on uncoated surfaces after 11 cycles of icing and de-icing tests.
Aging leads to a progressive loss of muscle function (MF) and quality (MQ: muscle strength [MS]/lean muscle mass [LM]). Power training and protein (PROT) supplementation have been proposed as efficient interventions to improve MF and MQ. Discrepancies between results appear to be mainly related to the type and/or dose of proteins used. The present study aimed at determining whether or not mixed power training (MPT) combined with fast-digested PROT (F-PROT) leads to greater improvements in MF and MQ in elderly men than MPT combined with slow-digested PROT (S-PROT) or MPT alone. Sixty elderly men (Age:69±7years; BMI:18-30kg.m-2) randomized into 3 groups: 1) Placebo+MPT (PLA; n=19); 2) F-PROT+MPT (n=21); 3) S-PROT+MPT (n=20) completed the intervention. LM, handgrip and knee extensor MS and MQ, functional capacity, serum metabolic markers, skeletal muscle characteristics, dietary intake and total energy expenditure were measured. The interventions consisted in 12 weeks of MPT (3-times/week;1h/session) combined with a supplement (30g: 10g per meal) of F-PROT (whey) or S-PROT (casein) or a Placebo. No difference was observed among groups for age, BMI, number of steps and dietary intake pre- and post-intervention. All groups improved significantly their LM, and lower limb MS/MQ, functional capacity, muscle characteristics and serum parameters following the MPT. Importantly, no difference between groups was observed following the MPT. Altogether, adding 30 g PROT per day to MPT, regardless of the type, does not provide additional benefits to MPT alone in older men ingesting an adequate (i.e. above recommended daily allowance) amount of protein per day.
Chapter 6 explores the relation between scale and particularism, defined as targeted efforts by politicians to cultivate the support of specific citizens or groups of citizens (aka clients), and the allegiance of those citizens to their leader (aka patron). We begin by sketching a theory of how scale might impact particularism, arguing that scale affects the efficiency of particularistic strategies, politicians’ opportunities to monitor compliance, mutual feelings of obligation between patron and client, and opposition to particularistic politics. On the basis of these assumptions, we expect higher levels of particularism in smaller communities. Next, we examine the question empirically using a variety of indicators including partisanship, targeted campaign expenditures, pork or earmarks, constituency service, vote-buying, clientelism, and corruption. Our analysis tends to confirm the notion that smaller polities, and smaller districts, are especially prone to the development of particularistic ties between leaders and their constituents. We however do not regard extant studies of size and corruption as dispositive. A brief conclusion draws together the results of these analyses.
Introduction: The elderly (65 yo and more) increase in Canada is well documented along with a disproportionate use of Emergency Departments after a minor injury. These patients requires specific care given a 16% risk of functional decline following a visit to ED. To prevent functional decline, a multidimensional assessment of the elderly is recommended in the emergency department. Objective: To determine if ED grip strength can predict functional decline at 3 or 6 months post-injury. Methods: A multicentre prospective study in 5 ED across Canada was realized between 2013 and 16. Patients 65 years old and over, autonomous in daily living activities and consulting the emergency department for minor trauma were recruited 7 days a week. Clinical-demographic data, functional status, fear of falling, number of falls in the last month, grip strength measurement were collected in the ED. Functional decline (loss of at least points to functional status) was calculated at 3 and 6 months. Descriptive statistics and linear regression model with repeated measurements were used to determine if the grip strength was predictive of functional decline at 3 or 6 months. Results: 387 patient were recruited. Mean age was 74 ± 7 years old, 52% were male. XXX experienced a fall in the last month. The initial maximum grip strength was (24 ± 10 intervention vs. 28 ± 13 control; p ≤ 0.05). grip strength is associated with pre-injury functional status (p < 0.0001) and fear of falling (p = 0.0001) but does not predict 3 or 6 month functional decline. Conclusion: Given the strong association with fear of falling and functional status at initial ED evaluation, we recommend that grip strength measurement could be included in a multidisciplinary geriatric emergency department assessment as needed.